The present invention relates to an electric hand tool, particularly a drill.
More particularly, it relates to an electric hand tool which has a housing, an electric motor accommodated in the housing and having a motor shaft, and a work spindle driven by the electric motor via a transmission gearing and carrying a tool receptacle.
Drills of this type are usually constructed as straight-drilling machines in which the drill spindle extends parallel to the motor shaft and axis of the housing and, for specific purposes, as angular-drilling machines in which the drill spindle is aligned at a right angle to the motor shaft and housing axis. In certain applications in which both straight and angular drilling must be carried out, as is the case in installations in American wooden house construction, the two machines must be at hand for continuous alternation.
A tool receptacle head serving as special accessory for a conventional drill is already known from DE 36 34 734 A1. It includes two separate housing parts having a hollow space which are located opposite one another and guided along a diagonally extending dividing plane. One housing part carries a support for a drive shaft and the other housing part carries a support for a power take-off shaft which projects out of the tool receptacle head and carries a drill chuck. The drive shaft and power take-off shaft are connected with one another by a double cardan or universal joint so as to be rigid with respect to torsion relative to one another. One hollow-cylindrical housing part of the tool receptacle head is placed on the spindle neck of the drill and the drill spindle of the drill is coupled with a driver by means of a double edge. The driver sits on the drive shaft so as to be fixed with respect to rotation relative to it. In the basic position of the two housing parts, the axes of the drive and power take-off shafts are flush with one another. Due to the relative rotation of the two housing parts, the power take-off shaft can be aligned in such a way that its axis encloses an acute or right angle with the axis of the drive shaft.
A standard drill can be re-tooled with this known tool receptacle head so as to form an angle drill which can also perform straight drilling.
While such a separate tool receptacle head serving as attachment is well-suited to the requirements of the home worker, it is not acceptable for professional machines.